aboutsummaryrefslogtreecommitdiffstats
path: root/target/linux/bcm27xx/patches-5.4/950-0026-i2c-bcm2835-Add-debug-support.patch
blob: 2d6d4f9aa3d5f4d918ffbf9050d20b60ebd7afbe (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
From d4739fb63aa2b47132b66225cef55eb66784df13 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
Date: Tue, 1 Nov 2016 15:15:41 +0100
Subject: [PATCH] i2c: bcm2835: Add debug support
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This adds a debug module parameter to aid in debugging transfer issues
by printing info to the kernel log. When enabled, status values are
collected in the interrupt routine and msg info in
bcm2835_i2c_start_transfer(). This is done in a way that tries to avoid
affecting timing. Having printk in the isr can mask issues.

debug values (additive):
1: Print info on error
2: Print info on all transfers
3: Print messages before transfer is started

The value can be changed at runtime:
/sys/module/i2c_bcm2835/parameters/debug

Example output, debug=3:
[  747.114448] bcm2835_i2c_xfer: msg(1/2) write addr=0x54, len=2 flags= [i2c1]
[  747.114463] bcm2835_i2c_xfer: msg(2/2) read addr=0x54, len=32 flags= [i2c1]
[  747.117809] start_transfer: msg(1/2) write addr=0x54, len=2 flags= [i2c1]
[  747.117825] isr: remain=2, status=0x30000055 : TA TXW TXD TXE  [i2c1]
[  747.117839] start_transfer: msg(2/2) read addr=0x54, len=32 flags= [i2c1]
[  747.117849] isr: remain=32, status=0xd0000039 : TA RXR TXD RXD  [i2c1]
[  747.117861] isr: remain=20, status=0xd0000039 : TA RXR TXD RXD  [i2c1]
[  747.117870] isr: remain=8, status=0x32 : DONE TXD RXD  [i2c1]

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/i2c/busses/i2c-bcm2835.c | 99 +++++++++++++++++++++++++++++++-
 1 file changed, 98 insertions(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -56,6 +56,18 @@
 #define BCM2835_I2C_CDIV_MIN	0x0002
 #define BCM2835_I2C_CDIV_MAX	0xFFFE
 
+static unsigned int debug;
+module_param(debug, uint, 0644);
+MODULE_PARM_DESC(debug, "1=err, 2=isr, 3=xfer");
+
+#define BCM2835_DEBUG_MAX	512
+struct bcm2835_debug {
+	struct i2c_msg *msg;
+	int msg_idx;
+	size_t remain;
+	u32 status;
+};
+
 struct bcm2835_i2c_dev {
 	struct device *dev;
 	void __iomem *regs;
@@ -68,8 +80,78 @@ struct bcm2835_i2c_dev {
 	u32 msg_err;
 	u8 *msg_buf;
 	size_t msg_buf_remaining;
+	struct bcm2835_debug debug[BCM2835_DEBUG_MAX];
+	unsigned int debug_num;
+	unsigned int debug_num_msgs;
 };
 
+static inline void bcm2835_debug_add(struct bcm2835_i2c_dev *i2c_dev, u32 s)
+{
+	if (!i2c_dev->debug_num_msgs || i2c_dev->debug_num >= BCM2835_DEBUG_MAX)
+		return;
+
+	i2c_dev->debug[i2c_dev->debug_num].msg = i2c_dev->curr_msg;
+	i2c_dev->debug[i2c_dev->debug_num].msg_idx =
+				i2c_dev->debug_num_msgs - i2c_dev->num_msgs;
+	i2c_dev->debug[i2c_dev->debug_num].remain = i2c_dev->msg_buf_remaining;
+	i2c_dev->debug[i2c_dev->debug_num].status = s;
+	i2c_dev->debug_num++;
+}
+
+static void bcm2835_debug_print_status(struct bcm2835_i2c_dev *i2c_dev,
+				       struct bcm2835_debug *d)
+{
+	u32 s = d->status;
+
+	pr_info("isr: remain=%zu, status=0x%x : %s%s%s%s%s%s%s%s%s%s [i2c%d]\n",
+		d->remain, s,
+		s & BCM2835_I2C_S_TA ? "TA " : "",
+		s & BCM2835_I2C_S_DONE ? "DONE " : "",
+		s & BCM2835_I2C_S_TXW ? "TXW " : "",
+		s & BCM2835_I2C_S_RXR ? "RXR " : "",
+		s & BCM2835_I2C_S_TXD ? "TXD " : "",
+		s & BCM2835_I2C_S_RXD ? "RXD " : "",
+		s & BCM2835_I2C_S_TXE ? "TXE " : "",
+		s & BCM2835_I2C_S_RXF ? "RXF " : "",
+		s & BCM2835_I2C_S_ERR ? "ERR " : "",
+		s & BCM2835_I2C_S_CLKT ? "CLKT " : "",
+		i2c_dev->adapter.nr);
+}
+
+static void bcm2835_debug_print_msg(struct bcm2835_i2c_dev *i2c_dev,
+				    struct i2c_msg *msg, int i, int total,
+				    const char *fname)
+{
+	pr_info("%s: msg(%d/%d) %s addr=0x%02x, len=%u flags=%s%s%s%s%s%s%s [i2c%d]\n",
+		fname, i, total,
+		msg->flags & I2C_M_RD ? "read" : "write", msg->addr, msg->len,
+		msg->flags & I2C_M_TEN ? "TEN" : "",
+		msg->flags & I2C_M_RECV_LEN ? "RECV_LEN" : "",
+		msg->flags & I2C_M_NO_RD_ACK ? "NO_RD_ACK" : "",
+		msg->flags & I2C_M_IGNORE_NAK ? "IGNORE_NAK" : "",
+		msg->flags & I2C_M_REV_DIR_ADDR ? "REV_DIR_ADDR" : "",
+		msg->flags & I2C_M_NOSTART ? "NOSTART" : "",
+		msg->flags & I2C_M_STOP ? "STOP" : "",
+		i2c_dev->adapter.nr);
+}
+
+static void bcm2835_debug_print(struct bcm2835_i2c_dev *i2c_dev)
+{
+	struct bcm2835_debug *d;
+	unsigned int i;
+
+	for (i = 0; i < i2c_dev->debug_num; i++) {
+		d = &i2c_dev->debug[i];
+		if (d->status == ~0)
+			bcm2835_debug_print_msg(i2c_dev, d->msg, d->msg_idx,
+				i2c_dev->debug_num_msgs, "start_transfer");
+		else
+			bcm2835_debug_print_status(i2c_dev, d);
+	}
+	if (i2c_dev->debug_num >= BCM2835_DEBUG_MAX)
+		pr_info("BCM2835_DEBUG_MAX reached\n");
+}
+
 static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev,
 				      u32 reg, u32 val)
 {
@@ -257,6 +339,7 @@ static void bcm2835_i2c_start_transfer(s
 	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr);
 	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len);
 	bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c);
+	bcm2835_debug_add(i2c_dev, ~0);
 }
 
 static void bcm2835_i2c_finish_transfer(struct bcm2835_i2c_dev *i2c_dev)
@@ -283,6 +366,7 @@ static irqreturn_t bcm2835_i2c_isr(int t
 	u32 val, err;
 
 	val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
+	bcm2835_debug_add(i2c_dev, val);
 
 	err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
 	if (err) {
@@ -349,6 +433,13 @@ static int bcm2835_i2c_xfer(struct i2c_a
 	unsigned long time_left;
 	int i;
 
+	if (debug)
+		i2c_dev->debug_num_msgs = num;
+
+	if (debug > 2)
+		for (i = 0; i < num; i++)
+			bcm2835_debug_print_msg(i2c_dev, &msgs[i], i + 1, num, __func__);
+
 	for (i = 0; i < (num - 1); i++)
 		if (msgs[i].flags & I2C_M_RD) {
 			dev_warn_once(i2c_dev->dev,
@@ -367,6 +458,10 @@ static int bcm2835_i2c_xfer(struct i2c_a
 
 	bcm2835_i2c_finish_transfer(i2c_dev);
 
+	if (debug > 1 || (debug && (!time_left || i2c_dev->msg_err)))
+		bcm2835_debug_print(i2c_dev);
+	i2c_dev->debug_num_msgs = 0;
+	i2c_dev->debug_num = 0;
 	if (!time_left) {
 		bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C,
 				   BCM2835_I2C_C_CLEAR);
@@ -377,7 +472,9 @@ static int bcm2835_i2c_xfer(struct i2c_a
 	if (!i2c_dev->msg_err)
 		return num;
 
-	dev_dbg(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
+	if (debug)
+		dev_err(i2c_dev->dev, "i2c transfer failed: %x\n",
+			i2c_dev->msg_err);
 
 	if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
 		return -EREMOTEIO;